Piston for internal-combustion engines.



A. RlEDLER.

PISTON FOR INTERNAL COMBUSTION ENGINES.

APPLICATNON FILED 00112. 1911.

1,270,663. Patented June 25,1918.

i 1 LA m 7 N i. I e "x Fig. 3

meman' c TE 51 ALOIS RIEDLER, F BERLIN, GERMANY.

PISTON FOR INTERNAL-COMBUSTION ENGINES.

To all whom it may concern Be it known that 1, Aims Brennan, a subject of the Emperor of Germany, residing atNo.'7 Rauchstrasse, Berlin, Germany. have invented certain new and useful improvements 1n Pistons for Internal-Combustion Engines' and I do hereby declare the following to be a clear, full, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being'had to the accompanying drawing, and to letters or figures of reference marked thereon, which form apart of this specification.

In pistons ofinternal combustion engines having a comparatively small cylinder diameter and running at a high speed any special cooling devices for the bottom of the plston may be dispensed with. The piston bottom is consequently only cooled indirectly by the cooling water of the cylinder. The heat flows from the bottom of the piston through the material to the wall of the cylinder and passes then from the latter into the cooling water.

The central portion of the piston bottom lying farthest away from the cooled cylinder walls is not sufficiently protected from overheating as the heat taken up by this portion is accumulated in the outer zones of the piston bottom, which are also overheated.

The central portion of the hitherto known piston bottoms is thus too much overheated and tends to crack owing to the great heat stresses.

The object of this invention is to pro- .vide a special heat conductor for carrying a part of the cylinder of an internal com- Specificetion of Iletters Patent: Patented June 25, 1918;. Application filed October 12, 1917. Serial No. 196,277.

bustion engine, showing the piston reciproeating in it partly in front. view and partlv in section. n

Fig. 1 is a vertical (-rossscction through the piston and Fig. 3 shows a scale.

-bdenotes a cylinder cooled by the cooling medium In this cylinder rcciprorates the piston rl with its shaft The piston bottom (l-.- limiting the combustion space has in the embodiment shown the shape of a flat plate; any other suitable form may be given, however, to this bottom. The piston shaft fis made preferably of a material which is a good conductor of heat, for instance cast iron, and the bottom (Z is made of the same material, or it may be made of steel in order to increase its strength. These constructions are well known in'the art.

The characteristic feature of this invendetail on an enlarged tion is constituted by the heat conductor- -e--, which is arranged "in such a manner beneath the underside of the bottom --din the interior of the piston that the heat taken up by the bottom -(I/- flows into the heat conductor -e andfrorn this, owing to the difference in temperature, into the wall of the cylinder. The arrows shown in Fig. 1 illustrate how this flow of heat takes place. The heat is carried oil fromthe ditierent parts of the piston bottom in the direction of the greatest dro in temperature and flows thus mainly rom the central portion of the bottom dinto the heat conductor -'-o-. The shape of the heat conductor --e influences the carry log off of the heat. With an increase of the cross-section from the central portion toward the piston shaft increases also the heat quantity carried oii from the central portion of the bottom d-. In order to obtain a good transmission or passage ofheat in the contacting surfaces of the heat conductor -e the end side and the cylindrical surface of the heat conductor'may also be provided with grooves, instead of being made smooth. 'These grooves may be provided with play (see Fig. 3) in the direction of expansion of the parts touching each other in order to prevent heat stresses. I v

As a result of the provision of a special v I the piston bottom'dth'e following ad tom in the required manner,

vantages are obtained:

The bottom ----d of the piston may be made of any suitable material and the thick- .ness of this bottom may be reduced as the heat conductor acts also as a support for the bottom Any reduction of the thickness of the bottom -0Z has the effect to reduce the differences'in temperature in the bottom,d. and the danger of a cracking of this bottom decrease in a corresponding'manner. The heat conductor arranged beneath the piston and made of a material, which is a good heat conductor, provides for snfliciently great cross sections for may ing off the heat taken up by the piston botwhile the small thickness of the bottom, which is of advantage with regard to the strength of the piston, may be retained.

The invention may be applied as well to 1 single-actingas double-acting pistons What I claim now as my invention isz 1. A piston of the ki'nd referred to, comprising a bottom part, a shaft part joining the bottom part and a heat conductor made 5 of a good heat conducting material and arranged within the shaft part, the end wall and the peripheral surface of said heat conductor being in contact with the piston bottom and shaft respectively. 2. A piston of the kind referred to, e.pmprising a bottom part, a shaft part joining the bottom part and a heat conductor made of a good heat conducting material and arranged within the shaft part, the end wall and the peripheral portion of said heat conductor being in contact with the piston bottom and shaft respectively and the contacting surfaces of the heat conductor, the piston bottom and shaft being provided with grooves.

I have signed my name.

ALOIS RIEDLER.

my invention, 

